Hydraulic draft gear



April 17, 1934. I R. R. STEVENS ,3

HYDRAULIC DRAFT GEAR 7 Filed QCh. 27 l928 /4-24za/a 7 8 9 INVENTOR ROY RSTEVENS vdfwl/ag ATTORNEY Patented Apr. 17, 1934 PATENT OFFICE 1,955,349 HYDRAULIC DRAFT GEAR Roy R. Stevens, Forest Hills, Pa., assignor, by

' mesne assignments, to Cardwell Westinghouse Company, Chicago, 111., a corporation of Delaware Application October 27, 1928, Serial No. 315,397

Claims. (01. 213-43) This invention relates to draft riggings for railway cars and has for its principal object the provision of a hydraulic draft rigging which is simple in construction, cheap to manufacture, and which 5 will effectively cushion the draft and bumng shocks to which a railway car is subjected.

Other objects and advantages will appear from the following more detailed description of my invention.

In the accompanying drawing; Fig. 1 is a plan view of my draft rigging mounted on'thecenter or [draft sills of a railway car; and Fig. 2 is an enlarged vertical longitudinal sectional view of the cushioning unit taken on the line 2--2 of Fig. 1.

Referring-now in detail to the drawing, the reference, character 1 indicates the usual center or draft sills which may comprise the usual spaced longitudinally disposed members to which are secured the usual front and rear draft lugs 2 and 3 respectively.

Disposed between the longitudinal members of the draft sills and supported by the usual strap member 4-. is a cushioning unit which comprises 5 front and rear casing sections 5 and 6, the inner end portion of the casing section 5 being telescoped within the open outer end portion of the casing section 6. The front-wall of the casing section 5 is provided with lateral extensions which are adapted to abut the front draft lugs 2, and

the rear wall of the casing section 6 is provided with like extensions which are adapted to abut the rear draft lugs 3.

Surrounding the cushioning unit and engaging 5 the rear wall of the casing section 6 thereof is the usual draft yoke 7, which has its outer end portion attached to the shank of a car coupler in any desired manner. The inner end of the coupler shank abuts the outer wall of the casing section 5.

The casing sections 5 and 6are connected together in such a manner that they are movable longitudinally relative to each other. In connecting these sections I prefer to have the rear 5 end portion of the casing section telescoped within'the open outer end portion ofthe section 6 and to prevent leakage from between these sections I preferably employ packing rings 8 which fit in annular packing ring grooves formed in the telescoped end of the casing section 5.

Extending through the casing section 6 and having screw-threaded connection therewith are bolts 9, the inner ends of which extend into longitudinal grooves 10 formed in the section 5 and are adapted to cooperate with abutments defining the ends of the'grooves to limit relative longitudinal movement of the casing sections.

The casing sections 5 and 6 define a chamber 11 which may be connected to a chamber 12 at one side of a valve piston 13 by way of passages 14 and 15, communication through said passages being controlled by a valve 16 which is normally maintained seated by the pressure of springs 1'7 contained in the chamber 11 and interposed between and engaging the section 5 and a spring seat 18 carried by the stem of the valve 16.

Contained in a chamber 20 at the upper side of the valve piston 13 is a spring 21, the pressure of which at all times tends to urge the valve piston downwardly. This chamber is connected to atmosphere through a pasage 22, which passage is so located that the valve piston 13 before it reaches the limit of its upward travel will lap it and close ofi communication of the chamber 20 with atmosphere.

Contained in the passage 14 is a check valve 23 which is adapted to control communication of the chamber 12 and passage 14 and is normally maintained seated by the pressure of a spring 24;

The chamber 11, passages 14 and 15 and chamber 12 are preferably filled with any suitable liquid which may be supplied through an opening leading to the passage 15, which opening may be closed by a plug 25 having screw-threaded connection with the casing section 6.

With the chambers 11 and 12 and passages 14 and 15 thus charged with liquid, the several parts of the draft rigging will be in their normal release positions as shown in the drawing.

I'hav'e shown the passage 15 enlarged at 26 to provide an air cushion above the liquid, the use of which cushion will hereinafter be more fully described, but it will be understood that in some instances this enlargement may be omitted so that the passage 15 will be completelyfilled with liquid.

When a draft gear, constructed in accordance with my invention, is subjected to buiiing shocks, the coupler shank, which is in contact with the front wall of the front casing section 5, moves this section rearwardly relative to the rear casing section 6. By this movement compressive forces are applied both to the spring 1'7 and the liquid content of the chamber 11. Inasmuch as the liduid is not compressible it forces the-valve backwardly from its seat against the resistance of the spring, which .is still further compressed, and

with the result that the passage for the liquid 1 into the chamber 12 is progressively restricted, resulting in frictional resistance to the flow. The increase in volume of the liquid in the chamber 12 is primarilyresisted by the compression of air in the enlargement or recess 26, in the upper portion of this chamber. When this compression has progressed until its resistance exceeds that of the spring 21 the valve piston or plunger '13 is forced upwardly, and additional and increasing resistance is thereby offered to the transfer of the liquid. This resistance is further augmented when the skirt of the plunger 13 closes the air port 22, further inward movement of the plunger resulting in the compression of the entrapped air in the chamber 20. The transfer of the liquid is therefore resisted by the valve 16, the entrapped air in the recess 26, the spring 21 and the entrapped air in the chamber 20, and in each instance the resistance is progressively augmented.

Upon the cessation of the externally applied forces the spring 1'7 immediately forces the valve 16 to its seat and the casing 5 outwardly. The chamber 11 being thus enlarged, the parts are all restored to normal position by the retransfer of liquid from the chamber 12 to the chamber 11 through the port controlled by the check-valve 23.

Under pulling strains, the action of the draft rigging is substantially the same as under buffing shocks, with the exception that the front casing section 5 abuts the front draft lugs 2 and the rear casing section 6 is moved forwardly relative to the section 5.

In cushioning light bufling and pulling shocks it will be understood that the valve piston 13 will not be moved upwardly a sufiicient distance to close the passage 22 leading from the chamber 20 to atmosphere, so that there will be no compression of fluid in the chamber 20 to additionally resist the shocks to which the rigging is subjected.

It will be noted that the passages 14 and 15 are somewhat tortuous and are formed thus for the purpose of resisting the flow of liquid therethrough, thus adding to the capacity of the rigging without changing the over all dimensions thereof. 1

While one illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the terms of the appended claims.

Having now described my invention, what I claim as new an ddesire to secure by Letters Patent, is:

1. In a hydraulic draft rigging, the combination with a casing comprising two relatively movable sections telescoped one within the other and having two compression chambers and passages adapted to connect one chamber with the other, a liquid in one of said chambers adapted to be displaced through said passages into the other of said chambers by the movement of one of said sections toward the other, a valve adapted to resist the flow of liquid through said passage and to be opened by the direct pressure thereupon of the liquid under compression, and means for increasing-the resistance of said valve according to the movement of one of said sections relative to the other.

2. In a hydraulic draft rigging, the combination with a casing comprising two relatively movable sections telescoped one within the other andhaving two compression chambers and passages adapted to connect one chamber with the other, a liquid in one of said chambers adapted to be displaced through said passages into the other of said chambers by the movement of either one of said sections toward the other, a'valve adapted to resist the flow of liquid through said passage and to be opened by the direct pressure thereupon of the liquid under compression, means for increasing the resistance of said valve according to the movement of one of said sections relative to the other, and means for resisting the displacement of the liquid in said other chamber.

3. In a hydraulic draft rigging, the combina tion with a casing comprising two relatively movable sections telescoped one within the other and having two compression chambers and passages adapted to connect one chamber with the other, a liquid in one of said chambers adapted to be displaced through said passages into the other of said chambers by the movement of either one of said sections toward the other, a valve adapted to resist the flow of liquid through said passage, means for increasing the resistance of said valve according to the movement of one of said'sections relative to the other, and spring pressed and fluid pressure means for resisting the displacement of the liquid in said other chamber.

4. In a hydraulic draft rigging, the combination with a casing comprising two relatively movable sections telescoped one within the other and having two compression chambers and passages adapted to connect one chamber with the other, a liquid in one of said chambers adapted to be displaced through said passages into the other of said chambers by the movement of either one of said sections toward the other, a valve adapted to resist the flow of liquid through said passage, means for increasing the resistance of said valve according to the movement of one of said sections relative to the other, spring pressed means adapted to resist .a predetermined dis placement of the liquid in said other chamber and fluid pressure means for resisting the further displacement of liquid in said other chamber.

5. In a draft gear, in combination, a pair of telescoping hollow liquidcontaining cylinders one thereof having a transverse partition provided with a tortuous duct leading therethrough, a valve for closing a port connecting two branches of the duct and openable by fluid pressure upon the relative approach of the cylinders, an expansion spring reacting against the outer end of the other cylinder for urging the valve to its seat, and compressible means for resisting the passage of fluid through the duct.

6. In a draft gear, a pair of telescoping cylinders having closed outer ends, a ported partition across one cylinder, a valve normally closing the port and openable'by liquid pressure developed by the relative approach of the cylinders, expansion spring means within the chamber common to both cylinders for urging the valve to its seat and being augmented by the relative approach of the cylinders, and elastic means resisting the flow of liquid through the port.

'7. In a-draft gear, in combination, a hollow cylinder having a closed end and an open end and a transverse ported partition, a cylinder telescoping the open end of the first-named cylinder and having its outer end closed, a valve for closing the partition port and openable by liquid pressure developed by the relative approach of the cylinders, an expansion helical spring for urging the valve to its seat and reacting against an abutment carried by the second-named cylinder, and elastic means resisting the flow of liquid past the valve.

8. In a draft gear, in combination, a telescopically compressible body having a compression chamber in ported connection with the variable chamber, a normally closed valve for the port openable by fluid pressure developed by the compression of the body, and an expansion spring urging the valve to its seat and reacting against a movable wall of the variable chamber.

9. In a hydraulic draft gear, in combination, a cylinder closed at one end only and having a transverse partition provided with ducts open respectively through its opposite faces and separated by a ported web normal to the cylinder axis, a cylinder telescoping the first-named cylinder and being open at its inner end and closed at its outer end, a valve normally closing the port of the web and having a stem projecting toward the open end of the first-named cylinder and carrying a spring seat, such valve being openable by fluid pressure as the two cylinders move toward each other, and a spring reacting between the seat and the closed end of the second-named cylinder for urging the valve to its seat-and resisting the inthrust of the second-named cylinder.

10. In a cushioning device, in combination, a chambered body for containing a liquid, a ported diaphragm crossing the body, a movable member in one compartment of the body for forcing liquid through the port, a valve for the port openable by the pressure developed by the advance of the movable member, and an expansion spring reacting between the movable member and the valve for providing an increasing resistance to the opening of the latter.

ROY R. STEVENS. 

